Poultice Sliver

All Slivers have "{2}, {T}: Regenerate target Sliver." (The next time that Sliver would be destroyed, instead tap it, remove it from combat, and heal all damage on it.)

Metallic Sliver

Sinew Sliver

Lancer Sliver

Sliver creatures you control have first strike.

Terramorphic Expanse

{T}, Sacrifice Terramorphic Expanse: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Synchronous Sliver

Azorius Chancery

Azorius Chancery enters the battlefield tapped.
When Azorius Chancery enters the battlefield, return a land you control to its owner's hand.
{T}: Add {W}{U}.

Meandering River

Meandering River enters the battlefield tapped.
{T}: Add {W} or {U}.

Azorius Guildgate

Azorius Guildgate enters the battlefield tapped.
{T}: Add {W} or {U}.

Disrupt

Counter target instant or sorcery spell unless its controller pays {1}.
Draw a card.

Glacial Floodplain

({T}: Add {W} or {U}.)
Glacial Floodplain enters the battlefield tapped.

Plains

Sidewinder Sliver

All Sliver creatures have flanking. (Whenever a creature without flanking blocks a Sliver, the blocking creature gets -1/-1 until end of turn.)

Island

Idyllic Beachfront

({T}: Add {W} or {U}.)
Idyllic Beachfront enters the battlefield tapped.

Mesmeric Sliver

All Slivers have "When this permanent enters the battlefield, you may fateseal 1." (To fateseal 1, its controller looks at the top card of an opponent's library, then they may put that card on the bottom of that library.)